error การ upload รูปภาพ ของ library upload ใน codeigniter ค่า...The filetype you are attempting to upload is not allowed.

public function upload_file()
	{
		$config['upload_path'] = "images/";
		$config['allowed_types'] = "jpg|gif|png";
		$config['max_size'] = 1024;
		$config['max_height'] = 1024;
		$config['max_width'] = 1024;
		
		$this->load->library("upload");
		$this->upload->initialize($config);
		
		if($this->upload->do_upload("picture")) //ถ้าอัพโหลดไม่มีปัญหา
		{
			$data = $this->upload->data();
			print_r($data);	  //แสดงค่า dataที่ได้
		}
		else 
		{
			echo $this->upload->display_errors();	
		}
	
	}